Express Diagnosis and Prediction of Remote Mass Mortality of Scallop Mizuhopecten yessoensis in Mariculture Farms Using Biomarkers

Abstract

The cage method for the cultivation of the seaside scallop Mizuhopecten yessoensis is the most developed and popular method at sea farms in Primorsky Krai (Sea of Japan). However, this method of mollusk cultivation requires the careful planning of farming activities. Recently, mariculture farms in different countries have often encountered the mass mortality of cultured hydrobionts. The causes of such diseases are not quite clear, and often their identification requires a large amount of time and financial expenditure. Therefore, the use of predictive mechanisms based on biomarkers can help identify hidden threats in cultured scallop organisms that lead to mass mortality. In this study, we propose a rapid diagnostic method for predicting the distant mass mortality of M. yessoensis cultured in cages using biomarkers. The assessment of the pathological state of cultured mollusks at earlier developmental stages using the DNA comet method and oxidative stress markers (malondialdehyde) will allow the diagnosis and prediction of significant losses of marketable individuals in marine farms. In this study, we evaluated different age groups of mollusks cultured in the different water areas of Peter the Great Bay (Sea of Japan). During the study, we found that the death of cultured mollusks increased with increasing DNA damage and the active accumulation of malondialdehyde in tissues. It was observed that in scallops aged 1+ cultured in Severnaya Bay, high levels of DNA molecule damage and malondialdehyde were registered in the digestive glands and gills, which subsequently led to the death of almost all marketable individuals aged 3+. Therefore, the work is of significant value in assisting the aquaculture industry in solving the emerging problems of scallop farming and preserving marketable products. The proposed markers effectively reflect the condition of molluscs under extreme conditions caused by various factors, making them highly suitable for monitoring studies and forecasts on aquaculture farms.